sudo brctl addbr br0
sudo ifconfig br0 up　　　
sudo ip tuntap add mode tap sim_tap0
sudo ifconfig sim_tap0  up
sudo brctl addif br0 sim_tap0
sudo brctl addif br0 eth0

sudo ip addr add 192.168.31.11/24 dev eth0

#ifconfig eth0 0.0.0.0
#dhclient br0

